Method and apparatus for transmitting downlink control channel information in carrier aggregation system

ABSTRACT

A method for transmitting control information by a base station in a communication system using a plurality of serving cells comprises transmitting is provided. The method includes a terminal, an identifier of a second serving cell identifying where control information regarding a first serving cell is transmitted, transmitting, to the terminal, a predetermined value of a carrier identifier used in the second serving cell, and transmitting the control information regarding the first serving cell including the carrier identifier having the predetermined value through the second serving cell.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims the benefit under 35 U.S.C. §119(e) of a U.S.Provisional application filed on Jan. 29, 2015 in the U.S. Patent andTrademark Office and assigned Ser. No. 62/109,333, a U.S. Provisionalapplication filed on Mar. 13, 2015 in the U.S. Patent and TrademarkOffice and assigned Ser. No. 62/132,650, a U.S. Provisional applicationfiled on May 14, 2015 in the U.S. Patent and Trademark Office andassigned Ser. No. 62/161,398, and a U.S. Provisional application filedon May 22, 2015 in the U.S. Patent and Trademark Office and assignedSer. No. 62/165,470, the entire disclosure of each of which is herebyincorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to methods and apparatuses fortransmitting downlink control signals by base stations to terminals andreceiving the same by terminals in wireless communication systems.

BACKGROUND

Generally, mobile communication systems have been developed to guaranteeuser activity while providing voice services. Mobile communicationsystems have been expanding service areas from voice to data, and thesystems have been grown to provide high-speed data services. However,more evolved mobile communication systems are required to live up tousers' desire for higher-speed services and lacking resources that arefaced by the current mobile communication systems.

As a system in development to respond to such demand, the 3rd generationpartnership project (3GPP) long term evolution (LTE) is now underway forstandardization as a next-generation communication system. LTE is thetechnology implementing high-speed packet-based communication with atransmission speed up to 100 Mbps. To that end, various approaches arebeing discussed, and some examples include simplifying the networkarchitecture to reduce the number of nodes over a communication path andmaking radio protocols as close to radio channel as possible.

The LTE system adopts hybrid automatic repeat request (HARQ) scheme thatre-transmits corresponding data through the physical layer when decodingfails at the initial stage of transmission. By the HARQ scheme, if thereceiver fails to precisely decode data, the receiver transmitsinformation indicating the decoding failure negative acknowledgement(NACK) to the transmitter so that the transmitter may re-transmit thecorresponding data through the physical layer. The receiver raises thedata reception capability by combining the data re-transmitted by thetransmitter with the data for which decoding has failed. Further, whenthe receiver precisely decode data, the receiver may transmitinformation indicating decoding succeeds (acknowledgement (ACK) to thetransmitter so that the transmitter may transmit new data.

FIG. 1 is a view illustrating a basic structure of time-frequency domainwhere data or a control signal is transmitted on downlink in an LTEsystem according to the related art.

In FIG. 1, the horizontal axis refers to the time domain, and thevertical axis refers to the frequency domain. In the time domain, theminimum transmission unit is an orthogonal frequency-divisionmultiplexing (OFDM) symbol, and Nsymb OFDM symbols 102 come together toconfigure one slot 106, and two slots come together to configure onesubframe 105. The slot is 0.5 ms long, and the subframe is 1.0 ms long.The radio frame 114 is a time domain unit consisting of ten subframes.In the frequency domain, the minimum transmission unit is subcarrier,and the bandwidth of the overall system transmission band consists of atotal of NBW subcarriers 104.

The basic resource unit in the time-frequency domain is resource element112 (RE), and this may be represented in OFDM symbol index andsubcarrier index. Resource block 108 (RB) or physical resource block(PRB) is defined with Nsymb (102) continuous OFDM symbols in the timedomain and N_(RB) continuous subcarriers 110 in the frequency domain.Accordingly, one RB 108 includes Nsymb×NRB REs 112.

Generally, the minimum transmission unit of data is RB. Generally, inthe LTE system, Nsymb=7, NRB=12, and, NBW and NRB are proportional tothe bandwidth of system transmission band. Data rate is increased inproportion to the number of RBs scheduled for the terminal. The LTEsystem defines six transmission bandwidths. For the FDD systemdifferentiating and operating downlink and uplink with frequencies,downlink transmission bandwidth may differ from uplink transmissionbandwidth. The channel bandwidth refers to an RF bandwidth correspondingto the system transmission bandwidth.

Table 1 represents the correlation between system transmission bandwidthand channel bandwidth defined in the LTE system. For example, the LTEsystem having a 10 MHz channel bandwidth has a transmission bandwidthconsisting of 50 RBs.

TABLE 1 Channel bandwidth BW_(Channel) [MHz] 1.4 3 5 10 15 20Transmission bandwidth 6 15 25 50 75 100 configuration N_(RB)

A downlink control signal is transmitted within first N OFDM symbols inthe subframe. Generally, N={1, 2, 3}. Accordingly, N is varied dependingon the amount of control signal to be transmitted in the currentsubframe. The control signal includes a control channel transmissionperiod indicator indicating how many OFDM symbols the control signal istransmitted over, scheduling information on downlink data or uplinkdata, and HARQ ACK/NACK signal.

In the LTE system, the scheduling information on downlink data or uplinkdata is transferred through downlink control information (DCI) from thebase station to the terminal. Uplink (UL) means radio link through whichthe terminal transmits data or control signal to the base station, anddownlink (DL) means radio link through which the base station transmitsdata or control signal to the terminal. DCI defines various formats, anda defined DCI format applies and operates depending on whetherscheduling information (UL (uplink) grant) for uplink data or schedulinginformation (DL (downlink) grant) for downlink data, whether the controlsignal is small-sized compact DCI, whether spatial multiplexing appliesusing multiple antennas, and whether DCI for power control or not. Forexample, DCI format 1 that is scheduling control signal (DL grant) fordownlink data is configured to include at least the following controlsignals.

Resource assignment type 0/1 flag): notifies whether resource assignmenttype is type 0 or type 1. Type 0 allocates resources in resource blockgroup (RBG) units by applying bitmap scheme. In the LTE system, thebasic unit of scheduling is resource block (RB) represented in time andfrequency domain resources, and RBG consists of a plurality of RBs andbecomes the basic unit of scheduling in the type 0 scheme. Type 1 allowsfor assignment of a particular RB in the RBG.

Resource block assignment: notifies RB allocated for data transmission.Resource represented according to system bandwidth and resourceassignment scheme is determined.

Modulation and coding scheme (MCS): notifies the size of transport blockthat is data to be transmitted and modulation scheme used for datatransmission.

Hybrid automatic repeat request (HARQ) process number: notifies processnumber of HARQ.

New data indicator: notifies whether HARQ initial transmission orre-transmission.

Redundancy version: notifies redundancy version of HARQ.

Transmit power control (TPC) command for physical uplink control channel(PUCCH): notifies transmit power control command for uplink controlchannel PUCCH.

The DCI undergoes channel coding and modulation and is transmittedthrough downlink physical control channel physical downlink controlchannel (PDCCH) or enhanced PDCCH (EPDCCH).

Generally, the DCI is subject to channel coding independently for eachterminal and is then configured of independent PDCCH and transmitted. Inthe time domain, the PDCCH is transmitted during the control signaltransmission period. The position of mapping of PDCCH in the frequencydomain is determined by the identifier (ID) of each terminal and spreadover the overall system transmission band.

The downlink data is transmitted through physical channel for downlinkdata transmission, physical downlink shared channel (PDSCH). PDSCH istransmitted after the control channel transmission period, and thespecific mapping position in the frequency domain, modulation scheme, orother scheduling information are notified by the DCI transmitted throughthe PDCCH.

Through the MCS consisting of five bits among the control signalsconstituting the DCI, the base station notifies the terminal of themodulation scheme that has applied to the PDSCH to be transmitted andthe size of data to be transmitted (transport block size; TBS). The TBScorresponds to the size before applying channel coding for errorcorrection to the transport block (TB) to be transmitted by the basestation.

The LTE system supports the following modulation schemes: quadraturephase shift keying (QPSK), 16 quadrature amplitude modulation (QAM),64QAM, and their respective modulation orders (Qm) are 2, 4, and 6. Thatis, QPSK may transmit two bits per symbol, 16QAM four bits per symbol,and 64QAM six bits per symbol.

3rd generation partnership project (3GPP) LTE Rel-10 adopted bandwidthexpanding technology to support more data traffic than LTE rel-8. Theabove technology which is called bandwidth extension or carrieraggregation (CA) may extend band to increase the volume of datatransmitted as much as the band extended as compared with LTE rel-8terminal transmitting data within a single band. Each of the bands iscalled component carrier (CC), and LTE rel-8 terminal has been specifiedto have one component carrier for each of downlink and uplink. Further,downlink component carrier and uplink component carrier connectedthereto via SIB-2 are collectively called cell. The SIB-2 connectionbetween the downlink component carrier and the uplink component carrieris transmitted through a terminal-dedicated signal. CA-supportingterminal may receive downlink data through multiple serving cells andtransmit uplink data.

In Rel-10, when the base station has difficulty sending physicaldownlink control channel (PDCCH) in a particular serving cell to aparticular terminal, a carrier indicator field (CIF) may be configuredas a field to indicate that PDCCH is transmitted through other servingcell and the corresponding PDCCH indicates the physical downlink sharedchannel (PDSCH) or physical uplink shared channel (PUSCH) of otherserving cell. The CIF may be configured in CA-supporting terminal. TheCIF has been set to be able to indicate other serving cell by addingthree bits to the PDCCH information in the particular serving cell, andthe CIF is included only upon cross carrier scheduling, and when CIF isnot included, cross-carrier scheduling is not performed. When CIF ispresent in downlink assignment information (DL assignment), the CIFindicates the serving cell where the PDSCH scheduled by DL assignmentinformation is to be transmitted, and when the CIF is present in uplinkresource assignment information (UL grant), the CIF indicates theserving cell where the PUSCH scheduled by the UL assignment informationgrant is to be transmitted.

As set forth above, in LTE-10, bandwidth extension technique, carrieraggregation (CA), has been defined to allow multiple serving cells to beconfigured in the terminal. The base station transmits downlink controlinformation for the multiple serving cells to the terminal for datascheduling.

Meanwhile, LTE-13 assumes scenarios in which up to 32 serving cells areconfigured, and now being discussed is the concept of expanding thenumber of serving cells up to 32 using unlicensed bands. When the numberof serving cells assigned to the terminal exceeds five, the existingthree-bit CIF may be expanded in size to increase the size of the PDCCHinformation. In this case, the terminal's receiving operation would bedifferent from existing ones, and thus, the existing three-bit CIF needsto be maintained.

The above information is presented as background information only toassist with an understanding of the present disclosure. No determinationhas been made, and no assertion is made, as to whether any of the abovemight be applicable as prior art with regard to the present disclosure.

SUMMARY

Aspects of the present disclosure are to address at least theabove-mentioned problems and/or disadvantages and to provide at leastthe advantages described below. Accordingly, an aspect of the disclosureis to provide methods and apparatuses for permitting cross-carrierscheduling when transmitting downlink control signals to multiple cellswhile maintaining the three-bit carrier indicator field (CIF) inwireless communication systems supporting carrier aggregation.

The first disclosure provides methods and apparatuses for transmittingaperiodic channel information for multiple cells by maintaining thethree-bit CIF in the wireless communication system supportive of carrieraggregation.

An embodiment of the first disclosure provides a cross-carrierscheduling method and apparatus in a wireless communication system.

An embodiment of the first disclosure provides a method and apparatusfor keeping the size of a cross carrier indicator to have apredetermined number of bits in a wireless communication system.

An embodiment of the first disclosure provides a method and apparatusfor providing information between a cross carrier indicator and a cellidentifier to a terminal in a wireless communication system.

An embodiment of the first disclosure provides a method and apparatusfor grouping a plurality of cells in a wireless communication system.

The second disclosure provides a method and apparatus for communicatinga measurement result by a terminal in a wireless communication system.

The second disclosure provides a method and apparatus for selecting ameasurement result in different methods depending on the type of acontrol message including a measurement result by a terminal in awireless communication system.

The second disclosure provides a method and apparatus for selecting ameasurement result by a terminal depending on whether a control messageis a measurement reporting message or a secondary cell group (SCG)failure message in a wireless communication system.

The third disclosure provides a method and apparatus for transmitting anintra-device coexistence message by a terminal in a wirelesscommunication system.

The third disclosure provides a method and apparatus for preventingpositioning signal interference in a wireless communication system.

The third disclosure provides a method and apparatus for transmittinginformation regarding uplink transmission affecting positioning signalsrelated to emergency calls in a wireless communication system.

In accordance with an aspect of the present disclosure, a method fortransmitting control information by a base station in a communicationsystem using a plurality of serving cells is provided. The methodincludes transmitting, to a terminal, an identifier of a second servingcell identifying where control information regarding a first servingcell is transmitted, transmitting, to the terminal, a predeterminedvalue of a carrier identifier used in the second serving cell, andtransmitting the control information regarding the first serving cellincluding the carrier identifier having the predetermined value throughthe second serving cell.

In accordance with an aspect of the present disclosure, a base stationfor transmitting control information in a communication system isprovided. The base station using a plurality of serving cells includes acontroller configured to generate an identifier of a second serving cellidentifying where control information regarding a first serving cell istransmitted and a predetermined value of a carrier identifier used inthe second serving cell, and generate the control information regardingthe first serving cell including the carrier identifier having thepredetermined value, and a transmitter configured to transmit theidentifier of the second serving cell, the predetermined value of thecarrier identifier, and the control information regarding the firstserving cell to a terminal through the second serving cell.

In accordance with an aspect of the present disclosure, a method fortransmitting a measurement result by a terminal in a wirelesscommunication system is provided. The method, when control informationincluding measurement results of one or more neighbor cells is to betransmitted, determining whether the control information is ameasurement result reporting message or a SCG failure message, when thecontrol information is the SCG failure message, selecting a bestmeasurement result of measurement results of serving frequencies for SCGserving cells and serving frequencies configured in the terminal andselecting a predetermined number of best measurement results ofmeasurement results of all non-serving frequencies configured in theterminal, generating the SCG failure message including the selectedmeasurement results, and transmitting the generated SCG failure messageto a base station.

In accordance with an aspect of the present disclosure, a terminal fortransmitting a measurement result in a wireless communication system isprovided. The terminal includes a controller configured to, when controlinformation including measurement results of one or more neighbor cellsis to be transmitted, determine whether the control information is ameasurement result reporting message or a SCG failure message, and whenthe control information is the SCG failure message, select a bestmeasurement result of measurement results of serving frequencies for SCGserving cells and serving frequencies configured in the terminal, andselect a predetermined number of best measurement results of measurementresults of all non-serving frequencies configured in the terminal, acontrol message processor configured to generate the SCG failure messageincluding the selected measurement results, and a transceivertransmitting the generated SCG failure message to a base station.

In accordance with an aspect of the present disclosure, a method fortransmitting control information by a terminal in a wirelesscommunication system is provided. The method includes detectinginterference with a positioning signal received by the terminal ordetecting interference with a positioning signal to be received by theterminal, determining whether the positioning signal is related to anemergency call, when the positioning signal is not related to theemergency call, determining whether transmission of an IDC message isconfigured in the terminal, when the transmission of the IDC message isconfigured in the terminal, and the IDC message may be transmitted,generating an IDC message including first information related to theinterference with the positioning signal, and transmitting the generatedIDC message to a base station.

In accordance with an aspect of the present disclosure, a terminal fortransmitting control information in a wireless communication system isprovided. The terminal includes a controller configured to detectinterference with a positioning signal received by the terminal ordetecting interference with a positioning signal to be received by theterminal, determine whether the positioning signal is related to anemergency call, when the positioning signal is not related to theemergency call, determine whether transmission of an IDC message isconfigured in the terminal, and when the transmission of the IDC messageis configured in the terminal, and the IDC message may be transmitted,generate an IDC message including first information related to theinterference with the positioning signal, and a transceiver configuredto transmit the generated IDC message to a base station.

Other aspects, advantages, and salient features of the disclosure willbecome apparent to those skilled in the art from the following detaileddescription, which, taken in conjunction with the annexed drawings,discloses various embodiments of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certainembodiments of the present disclosure will be more apparent from thefollowing description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is a view illustrating a basic structure of time-frequency domainwhich is radio resource domain where data or a control signal istransmitted on downlink in a long term evolution (LTE) system accordingto the related art;

FIGS. 2A and 2B are views illustrating communication systems accordingto various embodiments of the present disclosure;

FIG. 3 is a view illustrating a cross-carrier scheduling schemeaccording to an embodiment of the present disclosure;

FIG. 4 is a view illustrating a scheme of grouping and cross-carrierscheduling cells according to an embodiment of the present disclosure;

FIG. 5A is block diagrams illustrating the structure of a base stationaccording to an embodiment of the present disclosure;

FIG. 5B is a view illustrating an operation of a base station accordingto an embodiment of the present disclosure;

FIG. 6A is block diagrams illustrating the structure of a terminalaccording to an embodiment of the present disclosure;

FIG. 6B is a view illustrating an operation of a terminal according toan embodiment of the present disclosure;

FIG. 7 is a view schematically illustrating the structure of an LTEsystem according to an embodiment of the present disclosure;

FIG. 8 is a view schematically illustrating the radio protocol structurein an LTE system according to an embodiment of the present disclosure;

FIG. 9 is a view schematically illustrating a carrier aggregationoperation in a base station in an LTE system according to an embodimentof the present disclosure;

FIG. 10 is a view schematically illustrating a carrier aggregationoperation between base stations in an LTE system according to anembodiment of the present disclosure;

FIG. 11 is a view illustrating an overall operation between a terminaland a master base station and secondary base station according to anembodiment of the present disclosure;

FIG. 12 is a view illustrating an operation of a terminal according toan embodiment of the present disclosure;

FIG. 13 is a view illustrating a configuration of a terminal accordingto an embodiment of the present disclosure;

FIG. 14 is a view illustrating a configuration of a base stationaccording to an embodiment of the present disclosure; and

FIG. 15 is a view illustrating an embodiment of the present disclosure.

Throughout the drawings, like reference numerals will be understood torefer to like parts, components, and structures.

DETAILED DESCRIPTION

The following description with reference to the accompanying drawings isprovided to assist in a comprehensive understanding of variousembodiments of the present disclosure as defined by the claims and theirequivalents. It includes various specific details to assist in thatunderstanding but these are to be regarded as merely exemplary.Accordingly, those of ordinary skill in the art will recognize thatvarious changes and modifications of the various embodiments describedherein can be made without departing from the scope and spirit of thepresent disclosure. In addition, descriptions of known functions andconstructions may be omitted for clarity and conciseness.

The terms and words used in the following description and claims are notlimited to the bibliographical meanings, but, are merely used by theinventor to enable a clear and consistent understanding of the presentdisclosure. Accordingly, it should be apparent to those skilled in theart that the following description of various embodiments of the presentdisclosure is provided for illustration purpose only and not for thepurpose of limiting the present disclosure as defined by the appendedclaims and their equivalents.

It is to be understood that the singular forms “a,” “an,” and “the”include plural referents unless the context clearly dictates otherwise.Thus, for example, reference to “a component surface” includes referenceto one or more of such surfaces.

As used herein, the term “terminal” may be interchangeably used with theterm “user equipment (UE),” and the term “base station” may beinterchangeably used with the term “eNode-B” or “eNB.”

The description of embodiments of the present disclosure primarilytargets advanced evolved universal terrestrial radio access (E-UTRA) (orLTE-advanced (LTE-A)) supporting carrier aggregation but the subjectmatter of the present disclosure may also be applicable to othercommunication systems with a similar technical background with minorchanges without significantly departing from the scope of the presentdisclosure, and this may be possible under the determination of thoseskilled in the art to which the present disclosure pertains. Forexample, the present disclosure may be applicable to multicarrier highspeed packet access (HSPA) supporting carrier aggregation.

Considering that the number of licensed bands, such as LTE (unlessstated otherwise herein, this term is used to collectively refer toLTE-A or other advanced versions of LTE) frequency, is limited, it isbeing researched to provide LTE services on an unlicensed band such as 5GHz band, and this is called licensed assisted access (LAA). In adoptingthe LAA, it is considered to operate the LTE cell, which is of alicensed band, as a P cell and the LAA cell, which is of an unlicensedband, as an S cell by applying the carrier aggregation technique ofLTE-A. Accordingly, like in LTE-A, feedbacks generated in the LAA cellthat is an S Cell should be transmitted only from the P cell, and theFDD and TDD all may apply to the LAA cell. Now described is acommunication system in which LTE cells and LAA cells co-exist and arecombined through carrier aggregation.

Meanwhile, in the following detailed description, transmission of aparticular signal through a channel may be represented as transmissionof the channel for ease of description. For example, the term “controlchannel is transmitted” may mean that predetermined information istransmitted through the control channel. As another example, the term“PDSCH is transmitted” may mean that predetermined information istransmitted through the PDSCH. As another example, the term “PDSCH istransmitted through a serving cell” may mean that the PDSCH throughwhich predetermined information is transmitted uses a serving cellfrequency band. Hereinafter, the terms may be interchangeably used. Thisis why the above-described terms or phrases are often used in therelevant field to which the present disclosure pertains.

First Disclosure

FIGS. 2A and 2B are views illustrating communication systems accordingto various embodiments of the present disclosure.

Referring to FIGS. 2A and 2B, FIG. 2A illustrates an example in which anLTE cell 202 and an LAA cell 203 co-exist in one small base station 201over the network and the UE 204 communicates data with the base stationthrough the LTE cell 202 and the LAA cell 203. In this case, there is nolimitation on the duplex scheme of the LTE cell 202 or LAA cell 203.However, uplink transmission is performed only through the LTE cell 202when the LTE cell is a PCell.

FIG. 2B illustrates an example in which there are installed an LTE macrobase station 211 for broader coverage via LTE communication 216 and anLAA small base station 212 for increased data transmission over thenetwork via LAA communication 215, and in this case, there is nolimitation on the duplex scheme of the LTE macro base station 211 or theLAA small base station 212. However, uplink transmission from UE 214 isperformed only through the LTE base station 211 when the LTE basestation is a PCell. At this time, the LTE base station 211 and the LAAbase station 212 are assumed to have an ideal backhaul network.Accordingly, even when X2 communication 213 is possible between the basestations, so that uplink transmission is performed only through the LTEbase station 211, the LAA base station 212 may receive relevant controlsignal from the LTE base station 211 in real-time via the X2communication 213. In the system shown in FIGS. 2A and 2B, the LTE celland LAA cell may have a plurality of serving cells and together maysupport up to 32 serving cells. Accordingly, the schemes proposedaccording to the first disclosure may apply to both the system of FIG.2B and the system of FIG. 2A.

FIG. 3 is a view illustrating a cross-carrier scheduling schemeaccording to an embodiment of the present disclosure.

Referring to FIG. 3 exemplifies a scheduling operation for an LTE-Aterminal where component carrier #1 (CC#1, 309) and component carrier #2(DL CC#2, 319) are aggregated.

The example shown in FIG. 3 assumes that CC#2 319 is relativelyexcessively larger in downlink interference than CC#1 309, and thus thebase station has difficulty meeting a predetermined DCI receptioncapability when transmitting DCI for data transmission of CC#2 319 tothe terminal through CC#2 319. In such case, the base station maytransmit DCI through CC#1 309, and the terminal should be previouslyaware that the DCI informing the scheduling information of datatransmitted through CC#2 319 is lowered in CC#1 309.

Data may be error-corrected through HARQ retransmission, and thus, notrouble would occur when the base station transmits data via CC#2 319 tothe terminal. However, the base station adds a carrier indicator (CI)indicating which component carrier of scheduling information the DCIindicates to the DCI indicating the resource assignment information onthe scheduled data and transmission format and transmits the same. Forexample, CI=‘000’ denotes scheduling information for CC#1 309, andCI=‘001’ denotes scheduling information for CC#2 319.

Accordingly, the base station combines the DCI 301 indicating theresource assignment information and transmission format of the data 307scheduled for CC#1 with the carrier indicator 302 to configure anextended DCI. Then, the base station performs channel coding on the same(303), and then configures PDCCH through modulation and interleaving,and then maps to the PDCCH region 305 of CC#1, then transmits the same.Accordingly, the base station combines the DCI 311 indicating theresource assignment information and transmission format of the data 317scheduled for CC#2 with the carrier indicator 312 to configure anextended DCI. Then, the base station performs channel coding on the same(313), then configures PDCCH through modulation and interleaving, thenmaps to the PDCCH region 305 of CC#1, and then transmits the same.

In FIG. 3, the PDSCH in CC#2 may be scheduled through cross-carrierscheduling from CC#1, or the PDSCH in CC#2 may be scheduled throughself-scheduling from CC#2. When the PDSCH on CC#2 is scheduled throughcross-carrier scheduling from CC#1, the terminal may be set by a higherlayer signal to monitor the PDCCH/EPDCCH for scheduling the PDSCHtransmitted on CC#2 in a blind decoding scheme on CC#1. When the PDSCHon CC#2 is scheduled through self-carrier scheduling from CC#2, theterminal may be set by a higher layer signal to monitor the PDCCH/EPDCCHfor scheduling the PDSCH transmitted on CC#2 in a blind decoding schemeon CC#2.

Next, described with reference to FIG. 4 is a scheme for explicitlygrouping serving cells to maintain the size of carrier indicator field(CIF) bit field according to a first embodiment of the first disclosure.

FIG. 4 is a view illustrating an example of transmitting downlinkcontrol information including a carrier indicator by explicitly groupingserving cells and performing cross-carrier scheduling according to anembodiment of the present disclosure.

As seen in FIG. 4, Cell group 1 401 includes Pcell 402, Scell 1 403,Scell 2 404, Scell 3 405, Scell 4 406, Scell 5 407, Scell 6 408, Scell 7409. Cell group 2 411 includes Scell 8 412, Scell 9 413, Scell 10 414,Scell 11 415, Scell 12 416, Scell 13 417, Scell 14 418, and Scell 15419. Cell group 16 421 includes Scell 16 422, Scell 17 423, Scell 18424, Scell 19 425, Scell 20 426, Scell 21 427, Scell 22 428, and Scell23 429. Cell group 4 431 includes Scell 24 432, Scell 25 433, Scell 26434, Scell 27 435, Scell 28 436, Scell 29 437, Scell 30 438, and Scell31 439.

The base station may configure carrier aggregation for the terminal byconfiguring multiple cells through higher layer signal. The cellconfiguration information for configuring cells in the terminal mayinclude serving cell index information indicating the number of theserving cell. When the number of cells configured in the terminalthrough the higher layer signal is five or less, the cell indexinformation of serving cell may be mapped to CIF information as it is.For example, the serving cell index (ServCellIndex) value, 2, may bemapped to the CIF value, 2. Accordingly, the base station, whentransmitting downlink control channel (E)PDCCH) through other servingcell for scheduling on the PDSCH/PUSCH transmitted in one serving cell,may instruct the terminal using the three bits of the CIF mapped to thecell index information. When the number of cells is five or less, whichserving cell of data transmission the scheduling is for may be clearlyknown to the terminal even using the CIF alone.

However, when the number of cells exceeds five, a scheme as describedwith respect to the first embodiment is needed to keep the three bits ofCIF.

When the number of cells configured in the terminal is more than five,the base station may group the cells by performing grouping on eachserving cell. The grouping information may be configured and transmittedto the terminal by a higher layer signal, and each serving cell isincluded in only one group. Cell grouping may come into two schemes.First, cell grouping may come into a scheme where a particular cell inthe cell group is configured by a higher layer signal to performphysical uplink control channel (PUCCH) transmission, and the PUCCHincluding the uplink control signals for the cells in a cell group istransmitted through the particular cell. Second, cell grouping may beperformed in such a manner that cells are grouped to supportcross-carrier scheduling only among the cells in the cell group in orderto perform cross-carrier scheduling through transmission of the(E)PDCCH. The above two cell grouping schemes may be independent fromeach other, at least one of the cell grouping schemes may be set by ahigher layer signal, and the cell grouping as set may be configured andtransmitted to the terminal by a higher layer signal. In the followingembodiments, the second cell grouping scheme is assumed for the purposeof description.

When the number of cells configured in the terminal is more than fiveand not more than eight, although the serving cells belong to differentgroups, like in the case where the number of cells is five or less, thebase station may inform the terminal that the scheduling information isfor the one serving cell using the CIF three bits mapped to the cellindex information when transmitting downlink control channel (E)PDCCH)of other serving cell for scheduling on physical downlink shared channel(PDSCH)/physical uplink shared channel (PUSCH) transmitted in oneserving cell.

On the other hand, when the number of cells configured in the terminalis more than eight, the serving cell index of the serving cells includedin each cell group cannot be mapped to the CIF in one-to-onecorrespondence. This is why if the CIF is fixed to three bits, it mayindicate only eight serving cells, but the number of all the cellsexceeds eight. Accordingly, information as to which CIF the servingcells belonging to each group or serving cell index is mapped to isrequired, and the “mapping information of the CIF and the serving cellindexes of the serving cells in the cell group” may be configured byhigher layer information and may be transmitted to the terminal. Whenthe number of cells configured in the terminal exceeds five, this methodmay also apply. Or, even when the number of cells configured for theterminal capable of aggregating more than five or eight cells does notexceed five, the mapping information of the CIF and the serving cellindexes of the serving cells in the cell group may be transmitted by thehigher layer signal to the terminal according to such scheme.

The following Table 2 shows an example of the mapping information of theCIF and the serving cell indexes of the serving cells in the cell group.

TABLE 2 S cell 1 with serving cell index 1 in group 1 is CIF 1 S cell 2with serving cell index 2 in group 1 is CIF 2 S cell 3 with serving cellindex 3 in group 1 is CIF 3 S cell 4 with serving cell index 4 in group1 is CIF 4 S cell 5 with serving cell index 5 in group 1 is CIF 0 S cell6 with serving cell index 6 in group 1 is CIF 5 S cell 7 with servingcell index 7 in group 1 is CIF 6 P cell with serving cell index 0 ingroup 1 is CIF 7 S cell 8 with serving cell index 8 in group 2 is CIF 1S cell 9 with serving cell index 9 in group 2 is CIF 2 S cell 10 withserving cell index 10 in group 2 is CIF 3 S cell 11 with serving cellindex 11 in group 2 is CIF 4 S cell 12 with serving cell index 12 ingroup 2 is CIF 5 S cell 13 with serving cell index 13 in group 2 is CIF6 S cell 14 with serving cell index 14 in group 2 is CIF 7 S cell 15with serving cell index 15 in group 2 is CIF 0 S cell 16 with servingcell index 16 in group 3 is CIF 0 S cell 17 with serving cell index 17in group 3 is CIF 1 S cell 18 with serving cell index 18 in group 3 isCIF 2 S cell 19 with serving cell index 19 in group 3 is CIF 3 S cell 20with serving cell index 20 in group 3 is CIF 4 S cell 21 with servingcell index 21 in group 3 is CIF 5 S cell 22 with serving cell index 22in group 3 is CIF 6 S cell 23 with serving cell index 23 in group 3 isCIF 7 S cell 24 with serving cell index 24 in group 4 is CIF 4 S cell 25with serving cell index 25 in group 4 is CIF 3 S cell 26 with servingcell index 26 in group 4 is CIF 2 S cell 27 with serving cell index 27in group 4 is CIF 1 S cell 28 with serving cell index 28 in group 4 isCIF 0 S cell 29 with serving cell index 29 in group 4 is CIF 5 S cell 30with serving cell index 30 in group 4 is CIF 6 S cell 31 with servingcell index 31 in group 4 is CIF 7

Although in the above embodiment the cell group is a single one bygrouping one “scheduling (serving) cell” transmitting the (E)PDCCH andmultiple “scheduled (serving) cells” transmitting the PDSCH/PUSCHscheduled by the scheduling cell, it may also be possible to group intoa single group multiple scheduling cells transmitting the (E)PDCCH andmultiple scheduled serving cells transmitting the PDSCH/PUSCH scheduledby the multiple scheduling cells.

Meanwhile, the “mapping information of the CIF and the serving cellindexes of the serving cells in the cell group” as in the example shownin Table 2 may be known to the terminal using a predetermined equation.When the number of cells configured for the terminal exceeds five, oreven when the number of cells configured for the terminal capable ofaggregating more than five or eight cells does not exceed five, theequation may apply.

An example of the equation is as in Equation 1.

CIF=k mod M  Equation 1

Here, k is the serving cell index, and M is the number of serving cellsincluded in the cell group. M may be, e.g., five or eight.

As an example of applying Equation 1, when the number of serving cellsin cell group 4 is 8 (M=8), if Equation 1 applies to Scell 27 with theserving cell index 27 (k=27), CIF=27 mod 8=3. That is, the CIF value ofthe 27th cell in cell group 4 is 3.

As another example of configuring a CIF value, the CIF value may bedetermined in the ascending order of the serving cell indexes of theserving cells scheduled in each scheduling serving cell. When theserving cell indexes of the scheduling cells are 1, 9, and 17, and theserving cell indexes of the serving cells scheduled by the schedulingserving cells are as shown in Table 3, each serving cell index and CIFvalue are mapped as shown in Table 3.

TABLE 3 CIF assigned Scheduling cell index 0 1 2 3 4 5 6 7 Schedulingcell with 2 5 10 11 13 15 18 20 serving index 1 Scheduling cell with 3 46 8 12 14 16 19 serving cell index 9 Scheduling cell with 7 9 17 21 2223 24 25 serving cell index 17

The vertical axis in Table 3 above shows the cell indexes of thescheduling serving cells which are respectively 1, 9, and 17. Thehorizontal axis is the CIF value, and the shade area indicates the cellindexes of the serving cells scheduled. Assuming the serving cells areconfigured for the terminal in the order of cell indexes 2, 3, 4, 5, 6,7, 8, 10, 11, 12, 13, 14 . . . of the scheduled serving cells, the CIFvalue is assigned depending on what number the scheduled serving cell isscheduled by the scheduling serving cell.

In Table 3, for example, although the fourth serving cell is indeedconfigured third for the terminal, it is assigned CIF 1 because it isscheduled second in the ninth serving cell that is the schedulingserving cell. As another example, although the 13th serving cell isindeed configured eleventh for the terminal, it is assigned CIF 4because it is scheduled fifth in the first serving cell that is thescheduling serving cell.

When several scheduled serving cells are configured for the terminal tobe simultaneously scheduled by one scheduling cell, the CIF values areassigned in ascending order of serving cell indexes, and the terminaldetermines the serving cell transmitting data through the CIF values.Here, when the configuration of a particular serving cell is releasedand is removed from the cells configured for the terminal, the CIFvalues may be reconfigured in the ascending order of cell indexes exceptthe removed cell. For example, when among serving cells 2, 5, 10, 11,13, 15, 18, and 20 scheduled in the scheduling cell with a serving cellindex of 1, the 11th and 13th serving cells are removed from theconfiguration, and the CIFs of serving cells 2, 5, 10, 15, 18, and 20may be reconfigured to 0, 1, 2, 3, 4, and 5, respectively. Accordingly,when a scheduled cell is added to the scheduling cell with a servingcell index of 1, CIF values 7 and 8 are assigned to the added cell, andthe terminal receives data on the added serving cell according to theCIF values.

In another approach, when the configuration of a particular serving cellis released and the cell is removed from the cells configured for theterminal, the CIF values may maintain their CIF configuration regardlessof the removed cell. For example, when among serving cells 2, 5, 10, 11,13, 15, 18, and 20 scheduled in the scheduling cell with a serving cellindex of 1, the 11th and 13th-indexed serving cells are removed from theconfiguration, and the CIF values of serving cells 2, 5, 10, 15, 18, and20 may be left with their respective original values 0, 1, 2, 5, 6, and7. Accordingly, when a scheduled serving cell is added to the schedulingcell with a serving cell index of 1, CIF value 3 or 4 which is assignedto no cell are assigned to the added cell, and the terminal receivesdata on the added serving cell according to the CIF value 3 or 4 newlyassigned.

The serving cells in each group may be mapped to CIFs in a one-to-onecorrespondence by the above-described schemes, and the base station mayset serving cells where downlink control channel should be received tothe terminal by a higher layer signal and may perform cross-carrierscheduling on the cells in the same group by transmitting the downlinkcontrol channel.

For example, as shown in FIG. 4, when the base station transmitsscheduling information through cross-carrier scheduling in cell group 1401, the information indicating that the scheduling information forserving cell 2 404 and serving cell 3 405 is transmitted on serving cell1 403 is previously known to the terminal through higher layerinformation, and the terminal attempts to receive the schedulinginformation for serving cell 2 404 and serving cell 3 405 in servingcell 1 403.

Now described is a scheme for maintaining the size of the CIF bit fieldas three bits by implicitly grouping serving cells according to a secondembodiment of the first disclosure.

The scheme according to the second embodiment of the first disclosure isdescribed with respect to FIG. 4.

The second embodiment is for the base station to implicitly groupserving cells. Although the base station transmits cell groupinginformation to the terminal using higher layer information in the firstembodiment of the present disclosure, cell grouping is implicitlyperformed in the second embodiment of the present disclosure, and thus,the grouping information need not be transmitted to the terminal. In thesecond embodiment of the present disclosure, the serving cells belong toone group, and the base station may determine whether to group theserving cells. Accordingly, the base station need not transmit groupinginformation to the terminal. However, also in the second embodiment ofthe present disclosure, the base station may transmit groupinginformation to the terminal in some cases.

When the number of cells configured in the terminal is five or less, thecell index information of serving cell may be mapped to CIF informationas it is. When the number of cells configured in the terminal is morethan five and not more than eight, although the serving cells belong todifferent groups, like in the case where the number of cells is five orless, the base station may inform the terminal that the schedulinginformation is for the one serving cell using the CIF three bits mappedto the cell index information when transmitting downlink control channel(E)PDCCH) of other serving cell for scheduling on PDSCH/PUSCHtransmitted in one serving cell.

Meanwhile, when the number of cells configured in the terminal is morethan eight, the serving cell index of the serving cells included in eachcell group cannot be mapped to the CIF in one-to-one correspondence.This is why if the CIF is fixed to three bits, it may indicate onlyeight serving cells, but the number of all the cells exceeds eight.Accordingly, information as to which CIF the serving cells belonging toeach group or serving cell index is mapped to is needed, and suchinformation may be configured as higher layer information and may betransmitted to the terminal. When the number of cells configured in theterminal exceeds five, this method may also apply. Even when the numberof cells configured for the terminal capable of aggregating more thanfive or eight cells does not exceed five, the method may apply.

In a first scheme according to the second embodiment, the base stationmay also transmit the CIF value when transmitting the higher layerinformation on cross-carrier scheduling in the serving cell where thePDSCH is transmitted.

For example, in 3GPP Rel-10, the higher layer information forcross-carrier scheduling on the serving cell where the PDSCH istransmitted is as shown in Table 4.

TABLE 4

CrossCarrierSchedulingConfig-r10 ::= SEQUENCE {

 schedulingCellInfo-r10 CHOICE {

own-r10 SEQUENCE { -- No cross carrier scheduling

cif-Presence-r10 BOOLEAN

},

other-r10 SEQUENCE { -- Cross carrier scheduling

schedulingCellId-r10 ServCellIndex-r10,

pdsch-Start-r10 INTEGER (1..4)

}

 }

Meanwhile, in Table 4, information for cross-carrier scheduling is asshown in Table 5.

TABLE 5 other-r10 SEQUENCE { -- Cross carrier schedulingschedulingCellID-r10    ServCellIndex-r10,  pdsch-Start-r10  INTEGER(1..4)  }

For 3GPP Rel-13 supporting the CA of up to 32 cells,schedulingCellID-r13 indicating the cell index where the (E) PDCCH istransmitted is included instead of “schedulingCellID-r10” in Table 5 forRel-10. Meanwhile, “ServCellIndex-r13” may be set to one of (0..31).Meanwhile, when the (E)PDCCH is transmitted in the serving cell of“schedulingCellID-r13” having one value of (0..31), the CIF value(cif_value) indicating the serving cell where the PDSCH is transmittedmay be set to one value of (0..7).

That is, in the second embodiment of the first disclosure, the higherlayer information for cross-carrier scheduling for Rel-13 may beconfigured as shown in Table 6.

TABLE 6 other-r13 SEQUENCE {   -- Cross carrier schedulingschedulingCellID-r13 ServCellIndex-r13, cif_value-r13 INTEGER (0..7)pdsch-Start-r13 INTEGER (1..4) }

As described above, as the base station transmits the higher layerinformation on cross-carrier scheduling to the terminal, the terminalmay be aware that the (E)PDCCH where the scheduling information of thePDSCH of the serving cell is transmitted is transmitted in the servingcell having the value of “schedulingCellID-r13.” Further, as the CIFvalue of the (E)PDCCH is set to “cif-value-r13,” the terminal may beaware that the (E)PDCCH is the (E)PDCCH scheduling the PDSCH transmittedin the serving cell.

Here, the base station may internally, implicitly or explicitlyconfigure a serving cell group as shown in FIG. 4. When the number ofserving cells of one serving cell group in a configured serving cellgroup is eight, the number of serving cells where the PDSCH istransmitted as configured as a particular value of schedulingCellID-r10cannot exceed eight. For example, the number of serving cells where thePDSCH is transmitted whose “schedulingCellID-r10” is set to 1 cannotexceed eight. When the number of serving cells of one serving cell groupin a configured serving cell group is five, the number of serving cellswhere the PDSCH is transmitted as configured as a particular value ofschedulingCellID-r10 cannot exceed five. For example, the number ofserving cells where the PDSCH is transmitted whose“schedulingCellID-r10” is set to 1 cannot exceed five.

In a second scheme according to the second embodiment, the mappinginformation of each serving cell index and the CIF may be configured bya predetermined equation and be known to the terminal. The second schememay apply even when the number of cells configured for the terminalexceeds five, or even when the number of cells configured for theterminal capable of aggregating more than five or eight cells does notexceed five.

An example of the equation according to the second scheme is as in thefollowing Equation 2.

CIF=k mod K  Equation 2

Here, k is the serving cell index, and K is a constant. K may be, e.g.,five or eight.

When K=8, CIF=27 mod 8=3 for S cell 27 with a serving cell index of 27.That is, the CIF value of the 27th serving cell is 3.

As another example of configuring a CIF value, the CIF value may bedetermined in the ascending order of the serving cell indexes of theserving cells scheduled in each scheduling serving cell. When theserving cell indexes of the scheduling cells are 1, 9, and 17, and theserving cell indexes of the serving cells scheduled by the schedulingserving cells are as shown in Table 7, each serving cell index and CIFvalue are mapped as shown in Table 7.

TABLE 7 CIF assigned Scheduling cell index 0 1 2 3 4 5 6 7 Schedulingcell with 2 5 10 11 13 15 18 20 serving index 1 Scheduling cell with 3 46 8 12 14 16 19 serving cell index 9 Scheduling cell with 7 9 17 21 2223 24 25 serving cell index 17

The vertical axis in Table 7 above shows the cell indexes of thescheduling serving cells which are respectively 1, 9, and 17. Thehorizontal axis is the CIF value, and the shade area indicates the cellindexes of the serving cells scheduled. Assuming the serving cells areconfigured for the terminal in the order of cell indexes 2, 3, 4, 5, 6,7, 8, 10, 11, 12, 13, 14 . . . of the scheduled serving cells, the CIFvalue is assigned depending on what number the scheduled serving cell isscheduled by the scheduling serving cell.

In Table 7, for example, although the fourth serving cell is indeedconfigured third for the terminal, it is assigned CIF 1 because it isscheduled second in the ninth serving cell that is the schedulingserving cell. As another example, although the 13th serving cell isindeed configured eleventh for the terminal, it is assigned CIF 4because it is scheduled fifth in the first serving cell that is thescheduling serving cell.

When several scheduled serving cells are configured for the terminal tobe simultaneously scheduled by one scheduling cell, the CIF values areassigned in ascending order of serving cell indexes, and the terminaldetermines the serving cell transmitting data through the CIF values.Here, when the configuration of a particular serving cell is releasedand is removed from the cells configured for the terminal, the CIFvalues may be reconfigured in the ascending order of cell indexes exceptthe removed cell. For example, when among serving cells 2, 5, 10, 11,13, 15, 18, and 20 scheduled in the scheduling cell with a serving cellindex of 1, the 11th and 13th serving cells are removed from theconfiguration, and the CIFs of serving cells 2, 5, 10, 15, 18, and 20may be reconfigured to 0, 1, 2, 3, 4, and 5, respectively. Accordingly,when a scheduled cell is added to the scheduling cell with a servingcell index of 1, CIF values 7 and 8 are assigned to the added cell, andthe terminal receives data on the added serving cell according to theCIF values.

In another approach, when the configuration of a particular serving cellis released and the cell is removed from the cells configured for theterminal, the CIF values may maintain their CIF configuration regardlessof the removed cell. For example, when among serving cells 2, 5, 10, 11,13, 15, 18, and 20 scheduled in the scheduling cell with a serving cellindex of 1, the 11th and 13th-indexed serving cells are removed from theconfiguration, and the CIF values of serving cells 2, 5, 10, 15, 18, and20 may be left with their respective original values 0, 1, 2, 5, 6, and7. Accordingly, when a scheduled serving cell is added to the schedulingcell with a serving cell index of 1, CIF value 3 or 4 which is assignedto no cell are assigned to the added cell, and the terminal receivesdata on the added serving cell according to the CIF value 3 or 4 newlyassigned.

In the second scheme according to the second embodiment, the mappinginformation of the serving cell index and the CIF may be configured byhigher layer information as shown in Table 8 and be transmitted to theterminal.

TABLE 8 S cell 1 with serving cell index 1 is CIF 1 S cell 2 withserving cell index 2 is CIF 2 S cell 3 with serving cell index 3 is CIF3 S cell 4 with serving cell index 4 is CIF 4 S cell 5 with serving cellindex 5 is CIF 0 S cell 6 with serving cell index 6 is CIF 5 S cell 7with serving cell index 7 is CIF 6 P cell with serving cell index 0 isCIF 7 S cell 8 with serving cell index 8 is CIF 1 S cell 9 with servingcell index 9 is CIF 2 S cell 10 with serving cell index 10 is CIF 3 Scell 11 with serving cell index 11 is CIF 4 S cell 12 with serving cellindex 12 is CIF 5 S cell 13 with serving cell index 13 is CIF 6 S cell14 with serving cell index 14 is CIF 7 S cell 15 with serving cell index15 is CIF 0 S cell 16 with serving cell index 16 is CIF 0 S cell 17 withserving cell index 17 is CIF 1 S cell 18 with serving cell index 18 isCIF 2 S cell 19 with serving cell index 19 is CIF 3 S cell 20 withserving cell index 20 is CIF 4 S cell 21 with serving cell index 21 isCIF 5 S cell 22 with serving cell index 22 is CIF 6 S cell 23 withserving cell index 23 is CIF 7 S cell 24 with serving cell index 24 isCIF 4 S cell 25 with serving cell index 25 is CIF 3 S cell 26 withserving cell index 26 is CIF 2 S cell 27 with serving cell index 27 isCIF 1 S cell 28 with serving cell index 28 is CIF 0 S cell 29 withserving cell index 29 is CIF 5 S cell 30 with serving cell index 30 isCIF 6 S cell 31 with serving cell index 31 is CIF 7

Although in the second embodiment the implicit cell group is a singleone by grouping one “scheduling (serving) cell” transmitting the(E)PDCCH and multiple “scheduled (serving) cells” transmitting thePDSCH/PUSCH scheduled by the scheduling cell, it may also be possible toimplicitly group into a single group multiple scheduling cellstransmitting the (E)PDCCH and multiple scheduled serving cellstransmitting the PDSCH/PUSCH scheduled by the multiple scheduling cells.

Now described is a method for transmitting aperiodic channel informationaccording to a third embodiment of the first disclosure.

Methods as proposed herein to keep the CIF to have three bits have beenthus far described with respect to the first and second embodiments ofthe first disclosure. When explicitly grouping cells and transmittingthe cell grouping information to the terminal via higher layerinformation as in the first embodiment of the first disclosure orimplicitly grouping cells and transmitting related information to theterminal via higher layer information as in the second embodiment of thefirst disclosure in order to keep the CIF to have three bits, the basestation requests aperiodic channel information (or channel stateinformation) by transmitting the (E)PDCCH in the serving cell in thecell group. Accordingly, the terminal may measure the aperiodic channelinformation for the cell group configured by the higher layerinformation and the bit information mapped to the CSI request field ofthe (E)PDCCH or serving cells in the cell group or the cell group andmay transmit to the base station.

Assuming that the cell groups as shown in FIG. 4 are formed by theimplicit or explicit scheme, the base station may request the aperiodicchannel information for particular cells in the cell group using atwo-bit CSI request field. Here, the two bits configured in the CSIrequest field are previously configured by higher layer information toallow for request of aperiodic channel information for the particularcells and are transmitted to the terminal.

For example, when the CSI request field of the (E)PDCCH transmitted inScell 1 403 of cell group 1 is ‘10,’ the aperiodic channel informationfor particular cells, Scell 6 408 and Scell 7 409, in cell group 1 401may be configured to be measured and transmitted by higher layerinformation. When the CSI request field of the (E)PDCCH is ‘10,’ theterminal transmits the aperiodic channel information for Scell 6 408 andScell 7 409, which are the particular cells in cell group 1 401configured, through higher layer information. As another example whenthe CSI request field of the (E)PDCCH transmitted in Scell 1 403 of cellgroup 1 401 is ‘11,’ the aperiodic channel information for particularcells, Pcell 402, Scell 4 406 and Scell 5 407, in cell group 1 401 maybe configured to be measured and transmitted by higher layerinformation. When the CSI request field of the (E)PDCCH is ‘11,’ theterminal transmits the aperiodic channel information for Scell 6 408 andScell 7 409, which are the particular cells in cell group 1 401configured, through higher layer information.

Here, the base station may configure the cell group and serving cells inthe cell group by higher layer information so that the aperiodic channelinformation for the serving cells in other cell groups is measured andtransmitted together, and transmit to the terminal. For example, whenthe CSI request field of the (E)PDCCH transmitted in Scell 1 403 of cellgroup 1 401 is ‘10,’ not only may be configured to be measured andtransmitted the aperiodic channel information for Scell 6 408 and Scell7 409 by the higher layer information, but the channel information forScell 13 417 in cell group 2 411, Scell 16 422 and Scell 18 424 in cellgroup 3 421, and Scell 24 432 and Scell 27 435 in cell group 4 431 maybe measured and transmitted as well. As another example, when the CSIrequest field of the (E)PDCCH transmitted in Scell 1 403 of cell group 1401 is ‘11,’ not only may be configured to be measured and transmittedthe aperiodic channel information for Pcell 402, Scell 4 406 and Scell 5407 by the higher layer information, but the channel information forScell 8 412 and Scell 9 413 in cell group 2 411, Scell 19 425 in cellgroup 3 421, and Scell 28 436, Scell 29 437, and Scell 30 438 in cellgroup 4 431 may be measured and transmitted as well.

When the base station is rendered to measure and transmit the aperiodicchannel information only for the serving cells belonging to each cellgroup, the aperiodic channel information of all of the cell groups maybe requested only when as many (E)PDCCHs as the number of the cellgroups configured are transmitted. In contrast, as per the schemeproposed herein, the (E)PDCCH having the CSI request field configuredwith particular bits on a particular serving cell in a particular cellgroup may be transmitted to request the aperiodic channel information ofthe serving cells in all of the cell groups. Here, when the (E)PDCCH istransmitted to the terminal in particular serving cells in a particularcell group, the cell groups and the serving cells in the cell groups maybe configured by higher layer information according to the CSI requestfield value and the higher layer information may be transmitted to theterminal so that the aperiodic channel information for the serving cellsin other cell group may be requested. The terminal transmits to the basestation the aperiodic channel information for the particular cells inthe particular cell group from the configured higher layer information.

Meanwhile, not only the aperiodic channel information but also the(E)PDCCH triggering the uplink data channel for transmitting informationfor uplink control signals including uplink response signals(acknowledgement Ack)/negative acknowledgement Nack) may be transmittedin a particular serving cell in one cell group. Here, I_MCS in the(E)PDCCH is set to have a value among (29 . . . 31), and the size of theCSI request field may be set to two bits. Further, when the higher layerinformation is configured in the terminal so that the CSI request fieldmay request the aperiodic channel information for at least one or morecell groups and serving cells in the cell groups, the size (or number)of resource blocks where uplink data channel is transmitted may bedetermined in proportion to the number of cell groups configured forrequest of the aperiodic channel information or the number of servingcells configured in the cell groups. In the determined resource blocks,the terminal transmits to the base station the uplink data channelincluding only uplink control signal.

FIG. 5A is a view illustrating a base station according to an embodimentof the present disclosure.

Referring to FIG. 5A, the base station includes a transmitter includinga PDCCH block 505, a PDSCH block 516, a PHICH block 524, and amultiplexer 515, a receiver including a PUSCH block 530, a PUCCH block539, and a demultiplexer 549, a scheduler 503, and a controller 501determining the number of serving cells configured in the terminal andcontrolling grouping the serving cells, mapping serving cell index withCIF, and transmission of downlink control channel. Although multipletransmitters and receivers (except the PUCCH block) may be provided forcommunication on multiple cells, it is assumed that one transmitter andone receiver are provided for the purpose of description.

The controller 501 determines the number of serving cells configured inthe terminal and controls the grouping of serving cells, mapping betweenserving cell index and CIF, and the transmission of downlink controlchannel. Specific schemes therefor have been described above. Thecontroller 501 adjusts timing relations between physical channels forthe terminal, which the controller 710 is to schedule, by referencing,e.g., the volume of data to be transmitted to the terminal and theamount of resources available in the system and informs the scheduler503, the PDCCH block 505, the PDSCH block 516, the PHICH block 524, thePUSCH block 530, and the PUCCH block 539.

The PDCCH block 505 configures a control signal under the control of thescheduler 503, and the control signal is multiplexed with other signalsby the multiplexer 515. The PDSCH block 516 generates data under thecontrol of the scheduler 503 for the determination of the number ofserving cells configured in the terminal, grouping the serving cells,and mapping serving cell index with CIF, and the data is multiplexedwith other signals by the multiplexer 515.

The PHICH block 524 generates an HARQ ACK/NACK for the PUSCH receivedfrom the terminal under the control of the scheduler 503. The HARQACK/NACK together with other signals is multiplexed by the multiplexer515.

The multiplexed signals are generated into OFDM signals that are thentransmitted to the UE.

The PUSCH block 530 in the receiver obtains channel information for thesignal received from the terminal from the PUSCH.

The PUCCH block 530 obtains an uplink ACK/NACK or CQI from a signalreceived from the terminal. The obtained uplink ACK/NACK or CQI istransferred to the scheduler 503 and is used to determine whether tore-transmit the PDSCH and a modulation and coding scheme (MCS). Theobtained uplink ACK/NACK is transferred to the controller 501 to adjustthe transmission timing of PDSCH.

FIG. 5B is a view illustrating an operation of a base station accordingto an embodiment of the present disclosure.

In operation 571, the base station transmits to the terminal throughhigher layer information an identifier (schedulingCellID-r13) of thescheduling serving cell where control information including thescheduling information on the uplink or downlink regarding the currentserving cell is transmitted and/or a predetermined CIF value(cif_value-r13) used in the scheduling serving cell. Meanwhile, thecurrent serving cell and the scheduling serving cell may belong to thesame serving cell group. Further, as described above, the serving cellgroup may be implicitly or explicitly configured in the terminal.

In operation 573, the base station transmits the control informationregarding the current serving cell including the CIF having thepredetermined value through the (E)PDCCH of the scheduling serving cell.

In operation 575, the base station performs downlink transmissionthrough the (E)PDCCH of the current serving cell and/or uplink receptionthrough the (E)PUSCH of the current serving cell according to thescheduling information.

FIG. 6A is a view illustrating a UE according to an embodiment of thepresent disclosure.

The terminal includes a transmitter including a PUCCH block 605, a PUSCHblock 616, and a multiplexer 615, a receiver including a PHICH block624, a PDSCH block 630, a PDCCH block 639, and a demultiplexer 649, anda controller 601 grouping serving cells, mapping serving cell index withCIF in one group, and receiving downlink control channel upontransmission via higher layer information according to the firstdisclosure. Although multiple transmitters and receivers may be providedfor communication on multiple cells, it is assumed that one transmitterand one receiver are provided for the purpose of description.

The controller 601, when the higher layer information is transmittedfrom the base station according to the first disclosure, groups servingcells, maps serving cell index with CIF in one group, and receivesdownlink control channel. Specific schemes therefor have been describedabove. Further, the controller 601 transfers information described aboveaccording to the first disclosure to the PDSCH block 630, the PDCCHblock 639, the PUCCH block 605, and the PUSCH block 616.

The PUCCH block 605 configures HARQ ACK/NACK or CQI with the uplinkcontrol information (UCI) under the control of the controller 601controlling the storing of downlink data in a soft buffer, and the HARQACK/NACK or CQI is multiplexed with other signals by the multiplexer 615and transmitted to the base station. In the PUSCH block 616, uplink datais multiplexed with other signals in the multiplexer 615. Themultiplexed signals are generated into single carrier frequency divisionmultiple access (SC-FDMA) signals and the signals are transmitted to thebase station by referring to the period and offset in the method of UCIPUSCH transmission and cell grouping method according to the firstdisclosure.

The PHICH block 624 in the receiver separates, through the demultiplexer649, the PHICH signal from the signals received as per the DL/ULHARQ-ACK communication timing from the base station and then obtainswhether to HARQ ACK/NACK for the PUSCH. The PDSCH block 630 receivesfrom the base station the higher layer information related to thegrouping of the serving cells according to an embodiment of the firstdisclosure and the mapping between serving cell index and CIF in onegroup, separates the PDSCH signal through the demultiplexer 649, obtainsPDSCH data, and transfers whether there is an error as to the result ofdecoding the data to the PUCCH block 605 to adjust the generation of theuplink HARQ ACK/NACK. Further, the PDSCH block 630 transfers whetherthere is an error as to the decoding result to the controller 601 toadjust the timing when transmitting uplink HARQ ACK/NACK.

The PDCCH block 639 separates the PDCCH signal through the demultiplexer649 considering the grouping of serving cells, mapping between servingcell index and CIF in one group, and downlink control channel receptionaccording to an embodiment of the first disclosure and then decodes theDCI format to obtain the DCI from the decoded signal.

FIG. 6B is a view illustrating an operation of a terminal according toan embodiment of the present disclosure.

In operation 671, the terminal receives from the base station throughhigher layer information an identifier (schedulingCellID-r13) of thescheduling serving cell where control information including thescheduling information on the uplink or downlink regarding the currentserving cell is transmitted and/or a predetermined CIF value(cif_value-r13) used in the scheduling serving cell. Meanwhile, thecurrent serving cell and the scheduling serving cell may belong to thesame serving cell group. Further, as described above, the serving cellgroup may be implicitly or explicitly configured in the terminal.

In operation 673, the terminal receives the control informationregarding the current serving cell including the CIF having thepredetermined value through the (E)PDCCH of the scheduling serving cellfrom the base station.

In operation 675, the terminal performs downlink reception through the(E)PDSCH of the current serving cell and/or uplink transmission throughthe (E)PUSCH of the current serving cell according to the schedulinginformation.

As set forth above, according to the first disclosure, it may bepossible to perform cross-carrier scheduling on other cells whilemaintaining the three-bit CIF when transmitting downlink controlchannels in a system where up to 32 cells may be aggregated. Further,aperiodic channel information for multiple cells may be transmitted.

Further, it may be possible to perform cross-carrier scheduling on 32cells while maintaining the 3-bit CIF by implicitly or explicitlygrouping cells when the number of the cells configured for the terminalis more than five or eight and designating the cell index mapped to theCIF in each cell group. Accordingly, cross-carrier scheduling may besupported for up to 32 cells while maintaining the information bit sizeof downlink control channel. Further, aperiodic channel information formultiple cells may be transmitted according to the first disclosure.

Second Disclosure

Hereinafter, a second disclosure is described. First, the basic conceptof the second disclosure is described.

In the mobile communication system adopting multiple connections, themajor base station (eNB) is in charge of managing radio resources forthe terminal, sets a small cell group (SCG) for the terminal, or refersto a measurement result reported from the terminal in order to make adetermination, e.g., to change the PSCell for the terminal. Preferably,the terminal reports measurement results for the neighbor cell as wellas the serving cell depending on settings made by the base station, sothat the measurement result is reported to different neighbor cellsdepending on the purpose of reporting the measurement result.

According to the second disclosure, the terminal differently determinesa non-serving frequency and a serving frequency at which to report theneighbor cell measurement result for the serving frequency depending onthe type of event to trigger a measurement result report and reports theneighbor cell measurement result to the base station, thereby reducingthe size of the measurement result reporting message and allowing themaster base station to make a proper determination related to themanagement of radio resources.

The second disclosure relates to a method for reporting measurementresults for at least one or more neighbor cells and its major concept isas follows.

The terminal receives a control message to configure measurement fromthe base station, and the terminal having received the control messageperforms measurement on the neighbor cells of the serving base stationand non-serving base station and stores the measurement result.Thereafter, the terminal determines whether it is required to transmit acontrol message including the measurement result report information anddetermines whether the control message is a measurement result reportingmessage (MeasurementReport) or SCG failure reporting message(SCGFFailureInformation). For reference, for the measurement resultreporting message and the SCG failure reporting message, 3GPP TS 36.331may be referenced. Thereafter, the terminal determines a servingfrequency neighbor cell measurement result to be included in the controlmessage depending on the type of control message as follows.

If the control message is the measurement result reporting message, andpredetermined control information (hereinafter, first controlinformation) indicating to report the neighbor cell measurement resultof serving frequency has been received from the base station in thecontrol message configuring the measurement, the physical cell id (PCI)of the best measured cell among the neighbor cells is included in thecontrol message for each serving frequency for all the servingfrequencies currently set.

If the control message is the measurement result reporting message, andthe first control information has not been included in the messageconfiguring the measurement, the neighbor cell measurement result is notincluded in the control message for any serving frequency currently set,

If the control message is an SCG failure reporting message, themeasurement result value and physical cell id (PCI) of the best measuredcell per serving frequency for the serving frequency where the SCGserving cell has been set for the serving frequencies currently set areincluded in the control message regardless of whether the first controlinformation has been included in the control message configuring themeasurement.

Thereafter, the terminal determines a non-serving frequency neighborcell measurement result to be included in the control message dependingon the type of control message as follows.

That is, when the control message is the measurement result reportingmessage, as many neighbor cell measurement results as a predeterminedmaximum number for the first non-serving frequency are included, andwhen the control message is the SCG failure reporting message, as manyneighbor cell measurement results as another maximum number for thesecond non-serving frequency are included. The number of firstnon-serving frequencies is fixed to one, and the first non-servingfrequency is specified by a measured target associated with themeasurement result reporting message. Meanwhile, the neighbor cellmeasurement result for the first frequency includes a measurement resultvalue and a first layer cell identifier, the number of secondnon-serving frequencies is the same as the number of non-servingfrequencies configured in the terminal, and the neighbor cellmeasurement result for the second non-serving frequency includes anabsolute radio frequency channel number (ARFCN) indicating thenon-serving frequency, a measurement result value, and the first layercell identifier.

For the following reasons, different pieces of information are used asthe neighbor cell measurement information for the measurement resultreporting message and the neighbor cell measurement information of theSCG failure message.

The measurement result reporting message is a message that istransmitted from the terminal to the base station in a typical, normalenvironment in a normal radio resource management process, and it ispreferable to receive report of many neighbor cell measurement resultsfor the non-serving frequency indicated by the base station among thenon-serving frequencies configured in the terminal.

For example, assuming that four non-serving frequencies f1, f2, f3, andf4 are configured in the terminal, and f1 and f2 are non-servingfrequencies set for shift between frequencies, and f3 and f4 arenon-serving frequencies set for multi-connection setup, the neighborcell measurement results of f3 and f4 which are non-serving frequenciesrelated to the multi-connection setup may not be taken as usefulinformation in the measurement result reporting message related to theshift between frequencies. The SCG failure reporting message is amessage reported to the master base station for unpredicted SCG failure.Here, the SCG failure may be classified as an abnormal situation, suchas when the channel quality of PSCell among SCG serving cells has beendeteriorated in such extend that it is inappropriate for performingcommunication, or when random access has failed. Here, the informationneeded for the base station is information that allows for determinationof the serving cell to replace the PSCell where the failure hasoccurred, and accordingly, the neighbor cell measurement information forthe serving frequency of the SCG among the serving frequencies currentlyset corresponds to that. Further, another available scheme is to changethe SCG frequency into one of the non-serving frequencies as set, and inthat sense, the non-serving frequency neighbor cell measurementinformation is also useful information. However, as compared with themeasurement result reporting message including the neighbor cellmeasurement information for one non-serving frequency, the SCG failurereporting message including the neighbor cell measurement informationfor multiple non-serving frequencies requires the size of the neighborcell measurement information to be limited. Accordingly, the measurementresult reporting message includes multiple neighbor cell measurementresults for one non-serving frequency, and the SCG failure reportingmessage includes one neighbor cell measurement result per frequency formultiple non-serving frequencies.

Hereinafter, embodiments of the second disclosure are described.

FIG. 7 is a view schematically illustrating the structure of an LTEsystem according to an embodiment of the present disclosure.

Referring to FIG. 7, a radio access network of the LTE system includesnext-generation base stations (evolved node B, hereinafter, “ENB,” “NodeB,” or “base station”) 705, 710, 715, and 720, a mobility managemententity (MME) 725, and a serving gateway (S-GW). A user equipment(hereinafter, “UE” or “terminal”) 735 accesses an external networkthrough the ENB 705, 710, 715, and 720 and the S-GW 730.

The ENBs 705, 710, 715, and 720 of FIG. 7 correspond to legacy node Bsin the universal mobile telecommunication system (UNITS) system. TheENBs 705, 710, 715, and 720 are connected with the UE 735 through awireless channel and plays a more complicated role than the legacy nodeB.

Since in the LTE system all user traffic as well as real-time services,such as voice over Internet protocol (VoIP) service through an Internetprotocol is serviced through a shared channel, there is needed anapparatus that performs scheduling by compiling state information, suchas UEs' buffer states, available transmit power states, or channelstates, and the ENBs 705, 710, 715, and 720 are in charge of the same.One ENB typically controls multiple cells. The LTE system adopts, as aradio access technology, orthogonal frequency division multiplexing(hereinafter, “OFDM”) on a 20 MHz bandwidth in order to implement a highdata transmission speed. Further, the ENBs 705, 710, 715, and 720 useadaptive modulation & coding (AMC) that determines a modulation schemeand a channel coding rate in compliance with the channel state of theterminal 735.

The S-GW 730 is a device providing a data bearer, and the servinggateway 730 generates or removes a data bearer under the control of theMME 725. The MME 725 is an apparatus that is in charge of variouscontrol functions as well as mobility management functions for the UE735 and is connected with multiple base stations. The structure of LTEsystem has been described with reference to FIG. 7 according to anembodiment of the present disclosure. Next, the structure of radioprotocol in the LTE system according to an embodiment of the seconddisclosure is described with reference to FIG. 8.

FIG. 8 is a view schematically illustrating the radio protocol structurein an LTE system according to an embodiment of the present disclosure.

Referring to FIG. 8, the respective radio protocols of the UE and theENB in the LTE system, respectively, include Packet Data ConvergenceProtocol Layers (hereinafter, “PDCP layers”) 805 and 840, Radio LinkControl Layers (hereinafter, “RLC layers”) 810 and 835, and MediumAccess Control Layers (MAC layers) 815 and 830.

The packet data convergence protocol (PDCP) layers 805 and 840 are incharge of an operation such as compression/restoration, and the radiolink control (RLC) layers 810 and 835 reconfigure packet data units(PDUs) into a proper size to perform an automatic repeat request (ARQ)operation.

The MAC layers 815 and 830 are connected to several RLC layer devicesconfigured in one UE and multiplexes RLC PDUs into an MAC PDU anddemultiplexes the MAC PDU to generate RLC PDUs. The physical layers 820and 825 channel-code and modulate higher layer data into OFDM symbols,transmit the OFDM symbols through a wireless channel or demodulates OFDMsymbols received through a wireless channel, channel-decodes andtransfers the same to a higher layer.

The structure of radio protocol in the LTE system has been describedwith reference to FIG. 8 according to an embodiment of the presentdisclosure. Next, a carrier aggregation operation in the base station inthe LTE system is described with reference to FIG. 9, according to anembodiment of the present disclosure.

FIG. 9 is a view schematically illustrating a carrier aggregationoperation in a base station in an LTE system according to an embodimentof the present disclosure.

Referring to FIG. 9, one base station may generally transmit and receivemultiple carriers over several frequency bandwidths. For example, when acarrier 915 with a forward center frequency f1 and a carrier 910 with aforward center frequency f3 are transmitted from the base station 905,one UE conventionally communicates data using one of the two carriers.

However, a carrier aggregation-enabled UE may communicate data through anumber of carriers at the same time. The base station 905 may increasethe transmission speed of the UE 930 by allocating more carriers to thecarrier aggregation-enabled UE 930 depending on circumstances. Asdescribed above, aggregation of a forward carrier and backward carriertransmitted and received by one base station is referred to asintra-base station carrier aggregation. However, in some cases, unlikethat shown in FIG. 9, it may be needed to aggregate forward and backwardcarriers transmitted and received by different base stations.

The intra-base station carrier aggregation operation in the LTE systemhas been described with reference to FIG. 9 according to an embodimentof the second disclosure. Next, a carrier aggregation operation betweenbase stations in the LTE system is described with reference to FIG. 10,according to an embodiment of the second disclosure.

FIG. 10 is a view schematically illustrating a carrier aggregationoperation between base stations in an LTE system according to anembodiment of the present disclosure.

Referring to FIG. 10, when a base station 1 1005 communicates a carrierwith a center frequency f1 in area 1010, and a base station 2 1015communicates a carrier with a center frequency f2 in area 1020, if a UE1007 aggregates the carrier with the forward center frequency f1 and thecarrier with the forward center frequency f2, it ends up one UEaggregating carriers communicated by two or more base stations. In anembodiment of the second disclosure, this is denoted inter-ENB carrieraggregation. According to an embodiment of the second disclosure, theinter-ENB carrier aggregation is denoted dual connectivity (DC).

For example, the DC having been set means that inter-ENB carrieraggregation has been set, that one or more cell groups have been set,that a secondary cell group (SCG) has been set, that there has been setat least one secondary cell (SCell) controlled by a base station otherthan the serving base station, that a primary SCell (pSCell) has beenset, that a MAC entity has been set for serving eNB (SeNB), or that twoMAC entities have been configured in the terminal.

Meanwhile, the terms frequently used in describing embodiments of thepresent disclosure are briefly described below.

In a traditional sense, when one forward carrier transmitted from onebase station and one uplink carrier received by the base stationconstitute one cell, carrier aggregation may be appreciated as a UEcommunicating data through several cells at the same time. Here, themaximum transmission speed and the number of carriers aggregated have apositive correlation.

Hereinafter, in embodiments of the present disclosure, a “UE receivesdata through a forward carrier or transmits data through an uplinkcarrier” identically means that “data is communicated using a controlchannel and data channel corresponding to a frequency band and centerfrequency specifying the carriers. Particularly in the followingembodiments of the present disclosure, carrier aggregation isrepresented as “multiple serving cells are set” and the terms such asprimary serving cell (PCell) and secondary serving cell (SCell) oractivated serving cell are used. The terms have the same meanings asthose used in the LTE mobile communication system. In embodiments of thesecond disclosure, it should be noted that the terms “carrier,”“component carrier,” and “serving cell” may be interchangeably used.

In embodiments of the present disclosure, a group of serving cellscontrolled by the same base station is defined as a cell group orcarrier group (CG). Cell groups are divided into master cell groups(MCGs) and secondary cell groups (SCGs).

The MCG means a group of serving cells controlled by the base stationcontrolling PCells (hereinafter, master base station, MeNB), and the SCGmeans a group of serving cells controlled by the base station, which isnot the base station controlling the PCells, i.e., base stationcontrolling only SCells, (hereinafter, slave base station, SeNB).Whether a particular serving cell belongs to the MCG or SCG is informedthe terminal by the base station while setting up the correspondingserving cell.

One MCG and one or more SCGs may be configured in one terminal, and inembodiments of the second disclosure, for ease, the case where only oneSCG is set is considered, but although one or more SCGs are set up, thedescription of the second disclosure may apply as it is without anyaddition or change. PCell and SCell are terms to indicate the type of aserving cell configured in the terminal. A few differences lie betweenthe PCell and the Scell, e.g., the PCell always remains activated whilethe SCell may switch between activated state and inactivated state by aninstruction from the base station. The mobility of terminal iscontrolled centering on the PCell, and the SCell may be appreciated asan additional serving cell for data communication. In embodiments of thesecond disclosure, the PCell and the SCell mean the PCell and the SCelldefined in 36.331 or 36.321 of the LTE standard.

FIG. 11 is a view illustrating an overall operation between a terminaland a master base station and secondary base station according to anembodiment of the present disclosure.

In a mobile communication system including a terminal 1101, a masterbase station 1103, and a secondary base station 1105, the terminal 1101establishes an RRC connection with the master base station 1103 (1111).The establishment of the RRC connection is completed as the terminaltransmits an RRCConnectionRequest message to the base station, the basestation transmits an RRCConnectionSetup message to the terminal, and theterminal transmits an RRCConnectionSetupComplete message to the basestation. The RRCConnectionRequest message includes an identifier of theterminal, and the RRCConnectionSetupComplete messages includes variousconfiguration information for RRC connection, e.g., measurementconfiguration information (hereinafter, MeasConfig). The terminal maytransmit a service request control message to the core network using theRRCConnectionSetupComplete message, and the core network may instructthe master base station to configure a data radio bearer (DRB) that mayaccept the service request. The master base station performs an RRCconnection reconfiguration process with the terminal to configure, e.g.,DRB (1113). The RRC connection reconfiguration process is completed asthe base station transmits an RRCConnectionReconfiguration message tothe terminal, and the terminal transmits anRRCConnectionReconfigurationComplete message to the base station.

The RRCConnectionReconfiguration message includes multi-connectionconfiguration information or carrier aggregation information and allowsfor multi-connection configuration to the terminal or carrieraggregation to the terminal. The RRCConnectionReconfiguration messagemay also include a MeasConfig. The MeasConfig includes at least onemeasurement object information (hereinafter, measObject), at least onereporting configuration information (hereinafter, ReportConfig), and atleast one identifier (measurement identification, hereinafter measId).One measurement is specified by one measId, and one measId is connectedto one measObject and one ReportConfig. The measObject informationincludes carrier frequency information specified by a radio frequencychannel number (ARFCN). The ReportConfig information is information tospecify a condition of triggering the measurement result reportingmessage and includes information such as an indicator specifying thetriggering condition such as, e.g., ‘the measurement result reporting istriggered if the channel quality of neighbor cell is not less than apredetermined reference value,’ or ‘the measurement result reporting istriggered if the channel quality of neighbor cell is better than thechannel quality of serving cell by a predetermined reference value ormore,’ and relevant reference values. Further, when multiple servingfrequencies are set, control information (hereinafter, first controlinformation) indicating whether to include the best neighbor cellmeasurement result per serving frequency may also be included in thereporting configuration information. One measurement object and onereporting configuration are combined to configure one measurement. Theterminal, if a measurement result reporting condition for anymeasurement is met, generates a measurement result reporting message andtransmits to the base station, and includes the measId in themeasurement result reporting message in order to specify whichmeasurement the measurement result relates to.

The terminal periodically performs measurement on the measurement objectconfigured in the MeasConfig while performing a multi-connectionoperation with the master base station and the secondary base station(1115). The period at which the measurement is conducted is determinedby the DRX period configured in the terminal. The measurement object maybe set for the serving frequency and non-serving frequency of theterminal. If multi-connection and carrier aggregation has beenconfigured in the terminal, several serving cells are configured in theterminal. Accordingly, the number of serving frequencies configured inthe terminal is the same as the number of serving cells configured inthe terminal. The measurement for non-serving frequency is set for themobility of the terminal or load balancing. Accordingly, the number ofnon-serving frequencies configured in the terminal may vary depending onthe location or current serving frequency of the terminal, loadsituation per cell, and traffic of the terminal. As the number ofnon-serving frequencies set increases, the terminal needs to morefrequently adjust the RF circuit, and thus, the base station takescaution to prevent too many non-serving frequencies from being set perterminal.

At some time, a control message including a measurement result for theneighbor cell is generated (1117). For example, this occurs when ameasurement result reporting condition for one measurement as set is metor when an SCG failure occurs. If the channel status of the PSCell beingunder a predetermined reference lasts for a predetermined time or more,the terminal determines that an SCG failure occurred and generates anSCG failure reporting message. Or, if the measurement result reportingcondition for one of the measurements as set is met, the terminalgenerates a measurement result reporting control message.

The terminal includes the neighbor cell measurement result informationin the control message depending on the type of control message asfollows (1119) and transmits the control message to the master basestation (1121).

TABLE 9 Measurement report SCG failure indication Neighbor cellmeasurement result of Neighbor cell measurement result serving frequencyof serving frequency If the first control information was include themeasurement result of included in the report configuration the bestneighbor cell per serving information connected with the frequency forthe SCG serving cell corresponding measId, include the among the servingfrequencies measurement result of the best configured in the terminalregardless neighbor cell (the neighbor cell with of whether the neighborcell is the best channel quality except the included in the reportconfiguration serving cell at the corresponding information frequency)for each of all the serving Neighbor cell measurement result frequenciesconfigured in the of non-serving frequency terminal (i.e., all thefrequencies of include ARFCN information all of the serving cellsconfigured in specifying the non-serving the terminal). frequency andPCI and measurement Neighbor cell measurement result of results of mbest neighbor cells for non-serving frequency each of all frequencies,which are include the PCI and measurement not the current servingfrequency results of n best neighbor cells (i.e., neither MCG servingcell nor among neighbor cells measured at SCG serving cell is set),i.e., all the the frequency of measurement object non-servingfrequencies configured connected with the corresponding in the terminal,among the measId frequencies related to the where n is indicated by themeasurement object measurement object information where M is apredetermined integer, connected with the corresponding e.g., 1. meaId

The master base station 1103 records in the memory measurement resultinformation related to itself, e.g., measurement result informationrelated to the frequency managed by the master base station, from themeasurement result reporting message and refers to the measurementresult information for radio resource management determination such asmobility management. It includes, in a predetermined control message, ameasurement result report related to the secondary base station 1105,e.g., a measurement result report for the SCG serving frequency ormeasurement result report for a frequency managed by the secondary basestation 1105, and transfers to the secondary base station 1105 (1123).

The master base station 1103 and the secondary base station 1105 mayperform operations related to radio transmission resource management,e.g., changing PSCells, changing SCGs, or determination for handover,considering the measurement result reported from the terminal (1125).

FIG. 12 is a view illustrating an operation by a terminal according toan embodiment of the present disclosure.

In operation 1201, the terminal receives measurement configurationinformation (MeasConfig) from the master base station, and in operation1203, the terminal performs measurement on a configured measurementobject. One measurement object specifies one frequency, and onemeasurement object may specify a serving frequency or non-servingfrequency depending on the frequency of the serving cell configured inthe terminal. When such need occurs as to transmit a control messageincluding neighbor cell measurement result in operation 1205, theterminal determines the type of the control message in operation 1207.That is, the terminal determines whether the control message is ameasurement result reporting message or SCG failure reporting message.If it is the measurement result reporting message, it goes to operation1209 and if it is the SCG failure reporting message, it goes tooperation 1211.

In operation 1209, the terminal selects a measurement result meeting apredetermined first criterion as described above in connection withTable 9 among available neighbor cell measurement results, generates ameasurement result reporting message including the selected measurementresult and goes to operation 1213. Meanwhile, in operation 1211, theterminal selects a measurement result meeting a predetermined secondcriterion as described above in connection with Table 9 among availableneighbor cell measurement results, generates an SCG failure reportingmessage including the selected measurement result and goes to operation1213. In operation 1213, the terminal transmits the control messagegenerated in operation 1209 or 1211. To that end, the terminal sends arequest for transmission resource to the master base station, and whenthe transmission resource is assigned by the base station, the terminaltransmits the control message to the master base station (or through MCGserving cell).

FIG. 13 is a view illustrating a configuration of a terminal accordingto an embodiment of the present disclosure.

Referring to FIG. 13, according to an embodiment of the seconddisclosure, the UE may include a communication unit 1305, a controller1310, a multiplexing and demultiplexing unit 1315, a control messageprocessor 1335, and at least one of various higher layer processors 1320and 1325.

The multiplexing and demultiplexing unit 1315 and the controller 1310may configure an MAC device, and although not differentiated for ease inFIG. 13, when a DC is configured in the terminal, an MAC device for MCGand an MAC device for SCG may be separately configured.

The communication unit 1305 may receive data and a predetermined controlsignal through the forward channel of the serving cell and may transmitdata and a predetermined control signal through a reverse channel. Whenmultiple serving cells are configured, the communication unit 1305 mayperform data communication and communication of control signals throughthe multiple serving cells. The communication unit 1305 may include oneor more radio frequency (RF) circuit/front ends, and an RF circuit/frontend operation frequency may be set under the control of the controller1310. The communication unit 1305 may perform measurement betweenfrequencies at a predetermined time under the control of the controller1310 or may receive a signal from the current serving cell at apredetermined time, or may transmit a signal to the serving cell.

The multiplexing and demultiplexing unit 1315 may multiplex datagenerated in the higher layer processors 1320 and 1325 or the controlmessage processor 1335 or demultiplex data received from thecommunication unit 1305 and may transfer the resultant data to a properhigher layer processors 1320 and 1325 or the control message processor1335.

The control message processor 1335 is an RRC layer device, and mayprocess a control message received from the base station and perform anecessary operation. For example, it may receive an RRC control messageand transfer, e.g., measConfig or DRX information to the controller1310.

The higher layer processors 1320 and 1325 may be configured per service.The higher layer processors 1320 and 1325 may process data generated ina user service, such as file transfer protocol (FTP) or VoIP andtransfer the processed data to the multiplexing and demultiplexing unit1315, or may process data transferred from the multiplexing anddemultiplexing unit 1315 and transfer the processed data to a higherlayer service application.

The controller 1310 may identify a scheduling command received throughthe communication unit 1305, e.g., an uplink grant or downlinkassignment, and control the communication unit 1305 and the multiplexingand demultiplexing unit 1315 so that uplink transmission or downlinkreception is performed through a proper transmission resource at aproper time. The controller 1310 may be in charge of various controloperations of the terminal as described above. That is, the controller1310 may control the terminal's operations among those described inconnection with FIGS. 11, 12, and 13.

FIG. 14 is a view illustrating a configuration of a base stationaccording to an embodiment of the present disclosure.

The base station may include at least one of a communication unit 1405,a controller 1410, a multiplexing and demultiplexing unit 1420, acontrol message processor 1435, various higher layer units 1425 and1430, and a scheduler 1415.

The communication unit 1405 may transmit data and a predeterminedcontrol signal through a forward carrier and receive data and apredetermined control signal through a backward carrier. When multiplecarriers are configured, the communication unit 1405 may conductcommunication of data and control signals through the multiple carriers.

The multiplexing and demultiplexing unit 1420 may multiplex datagenerated in the higher layer processors 1425 and 1430 or the controlmessage processor 1435 or demultiplex data received from thecommunication unit 1405 and may transfer the resultant data to a properhigher layer processors 1425 and 1430, the control message processor1435 or the controller 1410.

The control message processor 1435 may process control messagetransmitted from the UE and perform necessary operations, or generatecontrol messages to be transferred to the UE and transfer the controlmessages to a lower layer.

The higher layer processors 1425 and 1430 may be configured per bearerand configure data transferred from an S-GW or other ENB in an RLC PDUand transfer to the multiplexing and demultiplexing unit 1420, orconfigure an RLC PDU transferred from the multiplexing anddemultiplexing unit 1420 in a PDCP SDU and transfer to the S-GW or theother ENB.

The scheduler 1415 may allocate transmission resources to the UE at aproper time considering the UE's buffer state and channel state and mayprocess the signal transmitted from the terminal to the communicationunit 1405 or perform a process to transmit a signal to the terminal.

The controller 1410 may be in charge of the operations related to theabove-described measurement and radio resource control. That is, thecontroller 1410 may control the base station's operations among thosedescribed in connection with FIGS. 11, 12, and 13.

Third Disclosure

Hereinafter, a third disclosure is described.

According to the third disclosure, the terminal's operation to addressintra-device interference is proposed.

When various communication protocols (e.g., legacy cellular networkprotocols, such as LTE and UMTS, wireless LAN and Bluetooth, globalnavigation satellite system (GNSS)/global positioning system (GPS))coexist in one terminal, such intra-device interference may occur wheretransmission under one communication protocol interferes with receptionunder another communication protocol. To address such intra-deviceinterference, the terminal reports occurrence of intra-deviceinterference to the base station, and the base station takes steps toaddress the interference based on the report from the terminal, e.g.,hand the terminal over to another frequency.

According to an embodiment of the present disclosure, there is describeda scheme to address the failure to properly receive positioning-relatedsignals, such as GNSS/GPS, by such intra-device interference.

The reception of GNSS positioning-related signals by the terminal may beinterfered by LTE uplink transmission by the terminal. In particular,when two or more LTE signals are simultaneously transmitted, receptionof signals with a frequency not adjacent to the LTE uplink frequency maybe negatively affected by inter modulation distortion (IMD).

For reference, the terminal receives GNSS positioning signals in variouscases as follows.

(1) in case of receiving a GNSS positioning signal to inform theemergency call center of the location of the terminal in associationwith an emergency call

(2) in case of receiving a global navigation satellite system (GNSS)positioning signal for car navigation

(3) in case of receiving a positioning signal for Internet positioningservices such as Googlemap

In the case of receiving a positioning signal related to emergency callby the terminal among the above cases, the reception of the emergencycall occurring in emergency is more critical than LTE uplinktransmission. In contrast, the reception of positioning signals iscritical for the remaining cases, but the LTE uplink transmission may betreated to be more critical under the determination of the base station.

An operation of the terminal to address the inter-device interferenceaccording to the present disclosure is as follows.

FIG. 15 is a view illustrating an operation by a terminal according toan embodiment of the present disclosure.

In operation 1501, the terminal detects the occurrence of interferencewith the reception of a positioning signal such as GPS/GNSS as aplurality of communication protocols coexist in the terminal. LTE uplinktransmission is performed through at least one LTE uplink, and whetherthe currently received positioning signal is interfered by the LTEuplink transmission signal is detected. However, detecting theoccurrence of interference in operation 1501 includes not only whetherinterference has occurred with a positioning signal already received butalso when a positioning signal to be received by the terminal ispredicted to be encountered with interference.

In operation 1503, the terminal determines whether the positioningsignal is related to an emergency call. When the positioning signal isrelated to the emergency call, it goes to operation 1505, and otherwise,to operation 1507. For reference, the emergency call refers to a callsent to an emergency call center, such as 911, and if the emergency callbegins, the terminal automatically runs positioning and transfers itslocation information to the call center. The radio protocol device ofthe terminal may fail to exactly determine whether the positioningprocess currently going on is related to the emergency call.Accordingly, when the emergency call begins, the application layer ofthe terminal notifies the RRC layer of the same. The RRC layer, uponreceiving the report that inter-device interference has occurred from aunit receiving positioning signals (GPS/GNSS), sees whether theemergency call is going on at the corresponding time and determineswhether the positioning process or the reception of positioning signalis related to the emergency call.

In operation 1507, the terminal determines whether IDS messagetransmission has been set up upon establishment of current RRCconnection. If the IDC message transmission has been set up, it goes tooperation 1509, otherwise to operation 1515. For reference, as per theprovider's policy or performance of the base station, even though theintra-device interference issue is reported by the IDC message, it maybe selected for the base station not to address such issue. In suchcase, the IDC message transmission leads to waste of radio transmissionresources and power of the terminal, and thus, the base station sets upthe transmission of IDC message through an RRC connectionreconfiguration message in the RRC connection reconfiguration process.In other words, the terminal transmits the IDC message only when the IDCmessage transmission is set up through the control message.

In operation 1509, the terminal determines whether the IDC messagetransmission is currently allowed. When the IDC message transmission iscurrently allowed, it goes to operation 1511, otherwise waits until theIDC message transmission is allowed. For reference, the current IDCmessage transmission is allowed in the following cases.

(1) In case intra-coexistence issue (hereinafter, referred to as the“IDC issue”) has occurred or goes on at least one LTE frequency, andafter the IDC message transmission has been set up, no intra-devicecoexistence indication message has been transmitted yet.

(2) In case the IDC issue has occurred or goes on at least one LTEfrequency, and although an IDC message has been transmitted, thefrequency where the IDC issue has occurred is different from thefrequency upon previous IDC message transmission.

In operation 1511, the terminal transmits an IDC message including firstinformation to a main base station (MeNB).

The first information includes information indicating that the LTEuplink transmission may interfere with reception of positioning signals(or serve as interference upon reception of the signals) and frequencyinformation regarding the LTE uplink interfering with reception ofpositioning signals and frequency information on the positioningsignals. The LTE uplink frequency information may be an ARFCN specifyingthe uplink or measured target identifier (measObjectId) information setto the downlink relating to the uplink (or paired or linked therewith).If the reception of positioning signal faces interference when two LTEuplink transmissions are made simultaneously, two information items(ARFCN or measObjectId) to specify the LTE uplink frequency affectingthe reception of the positioning signal are included for each.

Since the terminal has reported the IDC issue to the base station inoperation 1511, although the IDC issue occurs when the terminal performsuplink transmission as per the instruction by the base station, the basestation weighs more on the uplink transmission than on the reception ofpositioning signal. Accordingly, in operation 1513, the terminalperforms uplink transmission as per the instruction from the basestation.

Meanwhile, “the IDC message transmission has not been set up inoperation 1507” means that the base station has not addressed the IDCissue occurring in the terminal. Accordingly, the terminal performs itsself operation to receive the positioning signal in operation 1515.Specifically, the terminal controls the uplink transmission affectingthe reception of positioning signal according to predetermined priority.For example, the terminal, if two LTE uplink transmissions interferewith the reception of positioning signal, does not transmit one of thetwo according to the following rule.

(1) if the reception of positioning signal is interfered by simultaneoustransmission of the uplink signal from the PCell and the uplink signalfrom the SCell, the transmission of the SCell uplink signal is abandonedwhile the PCell uplink signal is transmitted

(2) if the reception of positioning signal is interfered by simultaneoustransmission of the uplink signal from the SCell and the uplink signalfrom the SCell, the transmission of the SCell uplink signal is abandonedwhile the MCG SCell uplink signal is transmitted

(3) if the reception of positioning signal is interfered by simultaneoustransmission of the uplink signal from the PCell and the uplink signalfrom the PSCell, the transmission of the PSCell uplink signal isabandoned while the PCell uplink signal is transmitted

Meanwhile, when the positioning signal is related to the emergency callin operation 1503, it goes to operation 1505.

In operation 1505, the terminal, although no intra-device coexistencecontrol message transmission is set up in the corresponding RRCconnection, and the corresponding time is not the time that theintra-device coexistence control message is permitted, includes firstcontrol information and second control information in an IDC message andtransmits the same through the MCG serving cell to the main basestation.

The second control information is information indicating that thereception of positioning signal facing interference by LTE uplinktransmission is related to an emergency call, and may be, e.g., one-bitinformation indicating that an emergency call is now going on.

Meanwhile, the terminal may re-transmit the IDC message if apredetermined condition is met. For example, the terminal mayre-transmit the IDC message at a predetermined period while theemergency call proceeds. As another example, when indicated for the LTEuplink transmission interfering with the reception of positioning signalafter the IDC message has been transmitted, the terminal may immediatelyre-transmit the intra-device co-existence report control message. Thatis, when the positioning signal is not related to the emergency callwhen transmitting the IDC message, the generated IDC message may betransmitted once, and when the positioning signal is related to theemergency call, the generated IDC message may be periodically or aperiodically repeatedly transmitted in a predetermined number of times.

While the present disclosure has been shown and described with referenceto various embodiments thereof, it will be understood by those skilledin the art that various changes in form and details may be made thereinwithout departing from the spirit and scope of the present disclosure asdefined by the appended claims and their equivalents.

What is claimed is:
 1. A method for transmitting control information bya base station in a communication system using a plurality of servingcells, the method comprising: transmitting, to a terminal, an identifierof a second serving cell identifying where control information regardinga first serving cell is transmitted; transmitting, to the terminal, apredetermined value of a carrier identifier used in the second servingcell; and transmitting the control information regarding the firstserving cell including the carrier identifier having the predeterminedvalue through the second serving cell.
 2. The method of claim 1, whereinthe identifier of the second serving cell and the predetermined value ofthe carrier identifier are transmitted using higher layer information.3. The method of claim 1, wherein the second serving cell is included ina same serving cell group as the first serving cell.
 4. The method ofclaim 3, wherein the serving cell group is implicitly or explicitlyconfigured in the terminal.
 5. The method of claim 1, wherein thecontrol information is downlink assignment information or uplinkassignment information.
 6. A base station for transmitting controlinformation in a communication system using a plurality of servingcells, the base station comprising: a controller configured to: generatean identifier of a second serving cell identifying where controlinformation regarding a first serving cell is transmitted and apredetermined value of a carrier identifier used in the second servingcell, and generate the control information regarding the first servingcell including the carrier identifier having the predetermined value;and a transmitter configured to transmit the identifier of the secondserving cell, the predetermined value of the carrier identifier, and thecontrol information regarding the first serving cell to a terminalthrough the second serving cell.
 7. The base station of claim 6, whereinthe identifier of the second serving cell and the predetermined value ofthe carrier identifier are transmitted using higher layer information.8. The base station of claim 6, wherein the second serving cell isincluded in a same serving cell group as the first serving cell.
 9. Thebase station of claim 8, wherein the serving cell group is implicitly orexplicitly configured in the terminal.
 10. The base station of claim 6,wherein the control information is downlink assignment information oruplink assignment information.
 11. A method for transmitting ameasurement result by a terminal in a wireless communication system, themethod comprising: when control information including measurementresults of one or more neighbor cells is to be transmitted, determiningwhether the control information is a measurement result reportingmessage or a secondary cell group (SCG) failure message; when thecontrol information is the SCG failure message, selecting a bestmeasurement result of measurement results of serving frequencies for SCGserving cells and serving frequencies configured in the terminal, andselecting a predetermined number of best measurement results ofmeasurement results of all non-serving frequencies configured in theterminal; generating the SCG failure message including the selectedmeasurement results; and transmitting the generated SCG failure messageto a base station.
 12. The method of claim 11, wherein the SCG failuremessage further includes identifiers of all the non-serving frequencies.13. A terminal for transmitting a measurement result in a wirelesscommunication system, the terminal comprising: a controller configuredto: when control information including measurement results of one ormore neighbor cells is to be transmitted, determine whether the controlinformation is a measurement result reporting message or a secondarycell group (SCG) failure message, and when the control information isthe SCG failure message, select a best measurement result of measurementresults of serving frequencies for SCG serving cells and servingfrequencies configured in the terminal, and select a predeterminednumber of best measurement results of measurement results of allnon-serving frequencies configured in the terminal; a control messageprocessor configured to generate the SCG failure message including theselected measurement results; and a transceiver configured to transmitthe generated SCG failure message to a base station.
 14. The terminal ofclaim 13, wherein the SCG failure message further includes identifiersof all the non-serving frequencies.
 15. A method for transmittingcontrol information by a terminal in a wireless communication system,the method comprising: detecting interference with a positioning signalreceived by the terminal or detecting interference with a positioningsignal to be received by the terminal; determining whether thepositioning signal is related to an emergency call; when the positioningsignal is not related to the emergency call, determining whethertransmission of an inter-device coexistence (IDC) message is configuredin the terminal; when the transmission of the IDC message is configuredin the terminal, and the IDC message may be transmitted, generating anIDC message including first information related to the interference withthe positioning signal; and transmitting the generated IDC message to abase station.
 16. The method of claim 15, wherein the first informationincludes information indicating that cellular uplink transmission in theterminal may interfere with reception of the positioning signal,frequency information regarding the uplink transmission interfering withthe reception of the positioning signal, and frequency informationregarding the positioning signal.
 17. The method of claim 15, furthercomprising: when the positioning signal is related to the emergencycall, generating an IDC message including the first information andinformation indicating that the positioning signal is related to theemergency call; and transmitting the generated IDC message to the basestation.
 18. The method of claim 15, wherein, when the positioningsignal is not related to the emergency call, the generated IDC messageis transmitted once, and when the positioning signal is related to theemergency call, the generated IDC message is repeatedly transmitted. 19.The method of claim 15, further comprising, upon generation of at leasttwo downlink transmissions affecting reception of the positioning signalrelated to the emergency call, disregarding the other downlinktransmissions except one with a higher priority of the at least twodownlink transmissions depending on a predetermined priority.
 20. Aterminal for transmitting control information in a wirelesscommunication system, the terminal comprising: a controller configuredto: detect interference with a positioning signal received by theterminal or detecting interference with a positioning signal to bereceived by the terminal, determine whether the positioning signal isrelated to an emergency call, when the positioning signal is not relatedto the emergency call, determine whether transmission of an IDC messageis configured in the terminal, and when the transmission of the IDCmessage is configured in the terminal, and the IDC message may betransmitted, generate an IDC message including first information relatedto the interference with the positioning signal; and a transceiverconfigured to transmit the generated IDC message to a base station. 21.The terminal of claim 20, wherein the first information includesinformation indicating that cellular uplink transmission in the terminalmay interfere with reception of the positioning signal, frequencyinformation regarding the uplink transmission interfering with thereception of the positioning signal, and frequency information regardingthe positioning signal.
 22. The terminal of claim 20, wherein, when thepositioning signal is related to the emergency call, the controller isfurther configured to generate an IDC message including the firstinformation and information indicating that the positioning signal isrelated to the emergency call; and wherein the transceiver is furtherconfigured to transmit the generated IDC message to the base station.23. The terminal of claim 20, wherein, when the positioning signal isnot related to the emergency call, the generated IDC message istransmitted once, and when the positioning signal is related to theemergency call, the generated IDC message is repeatedly transmitted. 24.The terminal of claim 20, wherein, upon generation of at least twodownlink transmissions affecting reception of the positioning signalrelated to the emergency call, the controller is further configured todisregard the other downlink transmissions except one with a higherpriority of the at least two downlink transmissions depending on apredetermined priority.